That was also in the Bruce Timm animated series. The first crossover with Joker teaming up with Lex where he stole a “Jade” dragon statue that supposedly killed it’s owners with a curse was actually made of Kryptonite and later in Justice League Unlimited had Lex diagnosed with cancer I think. Kryptonite has always been hazardous to humans.
Wasn’t there a storyline where Lex Luthor got terminal cancer from wearing a kryptonite ring all the time?
That was also in the Bruce Timm animated series. The first crossover with Joker teaming up with Lex where he stole a “Jade” dragon statue that supposedly killed it’s owners with a curse was actually made of Kryptonite and later in Justice League Unlimited had Lex diagnosed with cancer I think. Kryptonite has always been hazardous to humans.